The subject matter disclosed herein relates generally to switches, and, more particularly, to a linear actuating earthing switch.
In an electric power system, switchgear is generally referred to as the combination of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. These components are used to de-energize equipment to allow work to be done, and to clear faults downstream. An earthing switch may be installed in conjunction with the switchgear, and is used to provide a level of protection for maintenance personnel working on the electrical power system against the risk of accidental connection of a parallel source or energization by reverse power. The protection is provided by “earthing” the part of the installation that is to be worked on by interconnecting and connecting to an earth potential the phase and neutral conductors of the electric power system.
Use of an earthing switch is particularly important during maintenance operations, but also during normal function of the switchgear assemblies. Prior to earthing the phase and neutral conductors or bus terminals, it is mandatory to disconnect the upstream source of electrical power supplying the switchgear.
Traditional earthing switches employ a rotary mechanism that requires considerable volumetric space in which to operate. The rotary mechanism includes a plurality of switch blades, or movable contacts, that during opening and closing, swing or rotate about a fulcrum having a rotational axis. Because the vast majority of this space is reserved to accommodate momentary occupation by switch blades and spring actuators as the switch opens and closes, it makes the utilization of this space for any other purpose impossible. To further punctuate the inefficiency of the rotary mechanism used in earthing switches, these types of switches are often used in very compact structures where usable space is at a premium.
There is a need, therefore, for an improved earthing switch that is able to operate with linear motion instead of rotary or rotational motion in order to reduce the amount of space required for an earthing switch.